reproduction in organisms class 12th ncert solutions CBSE

 reproduction in organisms  class 12th ncert solutions CBSE

Q1. reproduction is the process y which an individual divides to form a new organism for reproduction further and the cycle continues, the reproduction enables continuity of species and would also recover the population graph. it also continues variation which when comes and gave survival advantage s to the people. hence, the reproduction of organisms is very important on this earth.

Q2.according to me, the better form of reproduction is sexual reproduction as to enables continuity and also variation among individuals which can give them survival advantage that leads to continuity. as asexual reproduction makes a clone of the parent and also doesn't produce any type of variation among individuals.

Q3.the organism produced by the asexual reproduction, the organism is termed a clone as a clone is the term used to describe any particular species similar genetically and morphologically individuals.

Q4.same answer is given in Q2.

Q5.the progeny produced by sexual reproduction is the variation of the parent that means it has different characteristics contained in parent s, whereas the asexual reproduction progeny is the clone which is similar to the parent and doesn't have any particular thing of variation and have larger chances of death.

Q6.the difference is given as  Q6. , vegetative reproduction is considered as asexual reproduction as it is an asexual reproduction as plants don't divide by sexual that means though pollination, it divides by growth of some vegetative propagules and some nodes which make them arise to give the new plant.

Q7.vegetative propagation is the type of process, of asexual reproduction of plants, in which the new plant arises from vegetative propagules. eg- rhizome of ginger, bulbil of agave, nodes of potato, etc.

Q8.juvenile phase is the phase in the organism that is defined as the growth phase in animals in which growth is taken place and leads to sexual maturity in organisms.

   reproductive phase is the phase the time of sexual maturity in which an individual gets sexually matured capable of reproducing organisms and this is a period of growth in the animals.

senescent phase is defined as the phase of growth in which old and aging occur, it is the phase after sexual maturity. in this phase the cells of the body get degenerate and the functioning of the body becomes irregular and slow. 

Q9.Higher organisms have resorted to sexual reproduction despite its complexity because sexual reproduction results in the multiplication and perpetuation of species and also contributes to the evolution of species by introducing variation much faster than asexual reproduction in a particular population. Sexual reproduction enables higher organisms to survive during unfavorable conditions.

Q10.meisoiss is the dividing capacity of the organism in which they get divides to form new organisms, this growth takes place and divides to form 4n. whereas gametogenesis is the term referred to as the production of gametes which n in number, which gives rise to zypote and hen embryo to form whole new individual n sexual reproduction . eg - human sperm and human egg called the ovum.

Q11.ovary- 2n

anther - 2n

egg-n

pollen -n

male gamete-n

zygote -2n

Q12.external fertilization is the fertilization that takes place in the medium, as in water. the fertilization of male and female gametes in which the gamates are to be fusion inside the water to form individuals. the disadvantage is it is more prone to predators and other organisms aquatic life which kills it and only a few of them be fertilized and save n the water. the number of individuals who grow is very less in number.

Q13.the difference between them is as follows, zoospore is produced by the fusion of egg and antherozoid in plants n which it grows into new plants, whereas the spite of formed by the fission of male and female gametes in the human female body, as it grows to form new individuals further.

Q14.gamateogenesis is the process of formation of gametes in male and female body separately which ovum in females and sperm in males which is n in number, embryogenesis is the formation of an embryo by zygote by dividing cells in the placenta of females of organisms which is 2n in number.

Q15.In sexual reproduction, events that occur after the formation of a zygote are called post-fertilization events. In flowering plants, the zygote is formed inside the ovule. After fertilization, the sepals, petals, and stamens of the flower wither and fall off. But the pistil remains attached to the plant. The zygote develops into the embryo and the ovules develop into the seed. The ovary develops into dying fruit that develops. a thick wall called the pericarp which is protective in – function. After dispersal, seeds germinate under favorable conditions to produce new plants.

Q16.bisexual flower is the flower in which the male and female gamete are present in a single plant. they are also called homothallic, monoecious plants.

Q17.do it yourself 

Q18.the offerings of oviparous animals at greater risk as compared to offspring in viviparous organisms, as they are contained in calcareous shells which may hatch by the predator and may be eaten by them whereas in viviparous the organisms which are about to be formed ingrown inside the body of the parent, it is more safe and free from predators.